JMHO, but somebody here is very mistaken...
Oh, you just cocked your pistol? What was that? Did someone just open a door? Could have just been the wind blowing. Everyone knows the sound of a shotgun racking, and if they don't, quite simply, their not in your house.
Furthermore, do you know how to handle this situation? Avoidance and evasion is the first key to your success. Did you know that most people can't remember the fist 30 seconds after waking up? Pistol?! Please. What kind of groupings do you normally shoot? How about under duress(probably extreme duress)? Assuming of course that you ARE a well versed shooter.
It's easy to say that you'll just bust out the AK47(yeah, I have one) and lay these fools to waste... "Yeah, I got a nuclear weapon up in here, how dare you bust in my crib"... Have you considered being scared, tending to your family, or how Adrenalin will effect you? And I'm not even gonna start about simply wounding an intruder...
I'll just stop there. The OP asked about home defense firearms. Home defense firearms=Pump shoty. No semi auto. No substitute. Keep it short so you can pull around the corners. Slug front, slug back, buck middle - finish first, finish last, chase middle.
About all I have to say about that.
A loud dog that knows how to bite would serve you better.